Add direct-connect multiplayer foundation

network/network_protocol.gd

@@ -0,0 +1,121 @@
+class_name NetworkProtocol
+extends RefCounted
+
+const PROTOCOL_VERSION: int = 1
+const GAME_BUILD: String = "prealpha"
+const MAX_DISPLAY_NAME_LENGTH: int = 48
+const MAX_PROFILE_ID_LENGTH: int = 96
+const MAX_NONCE_LENGTH: int = 96
+
+enum RejectionCode {
+	NONE,
+	MALFORMED_HANDSHAKE,
+	PROTOCOL_MISMATCH,
+	SERVER_FULL,
+	DUPLICATE_PROFILE,
+	AUTHENTICATION_TIMEOUT,
+	SERVER_SHUTTING_DOWN,
+	UNSUPPORTED_CLIENT,
+}
+
+
+static func make_client_hello(
+	profile_id: String,
+	display_name: String,
+	client_nonce: String,
+) -> Dictionary:
+	return {
+		"protocol_version": PROTOCOL_VERSION,
+		"game_build": GAME_BUILD,
+		"local_profile_id": profile_id,
+		"display_name": display_name,
+		"client_nonce": client_nonce,
+		"capability_flags": PackedStringArray(),
+		"cosmetic_snapshot": {},
+	}
+
+
+static func validate_client_hello(data: Variant) -> String:
+	if typeof(data) != TYPE_DICTIONARY:
+		return "Handshake payload is not a dictionary."
+	var payload: Dictionary = data
+	for key: String in [
+		"protocol_version",
+		"game_build",
+		"local_profile_id",
+		"display_name",
+		"client_nonce",
+		"capability_flags",
+		"cosmetic_snapshot",
+	]:
+		if not payload.has(key):
+			return "Handshake is missing %s." % key
+	if typeof(payload["protocol_version"]) != TYPE_INT:
+		return "Protocol version is invalid."
+	if typeof(payload["game_build"]) != TYPE_STRING:
+		return "Game build is invalid."
+	if typeof(payload["local_profile_id"]) != TYPE_STRING:
+		return "Profile ID is invalid."
+	if typeof(payload["display_name"]) != TYPE_STRING:
+		return "Display name is invalid."
+	if typeof(payload["client_nonce"]) != TYPE_STRING:
+		return "Client nonce is invalid."
+	if typeof(payload["capability_flags"]) not in [
+		TYPE_PACKED_STRING_ARRAY,
+		TYPE_ARRAY,
+	]:
+		return "Capabilities are invalid."
+	if typeof(payload["cosmetic_snapshot"]) != TYPE_DICTIONARY:
+		return "Cosmetic snapshot is invalid."
+	var profile_id: String = payload["local_profile_id"]
+	var display_name: String = payload["display_name"]
+	var nonce: String = payload["client_nonce"]
+	if (
+		profile_id.is_empty()
+		or profile_id.length() > MAX_PROFILE_ID_LENGTH
+		or display_name.is_empty()
+		or display_name.length() > MAX_DISPLAY_NAME_LENGTH
+		or nonce.is_empty()
+		or nonce.length() > MAX_NONCE_LENGTH
+	):
+		return "Handshake strings are outside allowed limits."
+	return ""
+
+
+static func make_server_hello(
+	accepted: bool,
+	rejection_code: RejectionCode,
+	session_id: String,
+	assigned_peer_id: int,
+	player_count: int,
+	max_players: int,
+) -> Dictionary:
+	return {
+		"accepted": accepted,
+		"rejection_code": int(rejection_code),
+		"protocol_version": PROTOCOL_VERSION,
+		"session_id": session_id,
+		"assigned_peer_id": assigned_peer_id,
+		"server_display_name": "NETFISHING",
+		"player_count": player_count,
+		"max_players": max_players,
+		"capability_flags": PackedStringArray(["movement_v1"]),
+	}
+
+
+static func rejection_text(code: int) -> String:
+	match code:
+		RejectionCode.PROTOCOL_MISMATCH:
+			return "The server uses a different network protocol."
+		RejectionCode.SERVER_FULL:
+			return "The server is full."
+		RejectionCode.DUPLICATE_PROFILE:
+			return "This local profile is already connected."
+		RejectionCode.AUTHENTICATION_TIMEOUT:
+			return "The server did not finish authentication."
+		RejectionCode.SERVER_SHUTTING_DOWN:
+			return "The server is shutting down."
+		RejectionCode.UNSUPPORTED_CLIENT:
+			return "This game build is not supported by the server."
+		_:
+			return "The server rejected the connection."